Fifty years ago today (Sept. 12), President John F. Kennedy whipped up support for NASA's fledgling Apollo program in a speech that contains perhaps the most famous words he ever uttered about space exploration.

Kennedy's stirring, soaring "moon speech," delivered at Rice University in Houston, laid out why the president believed sending astronauts to Earth's nearest neighbor by the end of the 1960s was so important. Kennedy had first aired that ambitious goal in May 1961, just six weeks after the Soviet Union's Yuri Gagarin became the first human to reach space.